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Justification for qualification based on EPPO PM 4 Standards
Justification for disqualification
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NAME OF THE ORGANISM: Pseudomonas amygdali pv. morsprunorum & P. avellanae pv. morsprunorum {Pseudomonas syringae pv. morsprunorum} (PSDMAM for P. amygdali & PSDMAL for P. avellanae)

GENERAL INFORMATION ON THE PEST

Name as submitted in the project specification (if different):

Pseudomonas syringae pv. mors-prunorum

Pest category:

Bacteria

1- Identity of the pest/Level of taxonomic listing:

Is the organism clearly a single taxonomic entity and can it be adequately distinguished from other entities of the same rank?

Yes

Is the pest defined at the species level or lower?:

Yes

Can listing of the pest at a taxonomic level higher than species be supported by scientific reasons or can species be identified within the taxonomic rank which are the (main) pests of concern?

Not relevant: Fruits (including hops) sector

If necessary, please list the species:

Is it justified that the pest is listed at a taxonomic rank below species level?

Yes

Conclusion:

Candidate: Fruits (including hops) sector

Justification (if necessary):

Various Pseudomonas spp. have been reported to be associated with bacterial canker disease (BCD) in Prunus spp. (for overview see Hulin et al., 2020; Table 1).
Pseudomonas syringae pv. morsprunorum has been split in two groups and renamed (see Hulin et al., 2020):
- P. amygdali pv. morsprunorum (PG03) (formerly P. syringae pv. morsprunorum Race 1, Psm1), and
- P. avellanae pv. morsprunorum (PG01b) (formerly P. syringae pv. morsprunorum Race 2, Psm2).
This RNQP summarysheet covers both taxa.

2 – Status in the EU:

Is this pest already a quarantine pest for the whole EU?

Presence in the EU:

Yes

List of countries (EPPO Global Database):

Czech Republic (1996); Denmark (1993); Finland (2011); France (1994); Germany (1993); Greece (1992); Ireland (1993); Italy (1992); Netherlands (1993); Poland (1992); Romania (1992); Sweden (1996)

Conclusion:

Justification (if necessary):

Data of the presence of this pest on the EU territory are available in EPPO Global Database (https://gd.eppo.int/).

HOST PLANT N°1: Prunus persica (PRNPS) for the Fruits (including hops) sector.

Origin of the listing:

Commission Implementing Directive (EU) 2014/98/EU and Commission Implementing Regulation (EU) 2019/2072

Plants for planting:

Plants intended for planting

3 - Is the pest already listed in a PM4 standard on the concerned host plant?

Yes

Conclusion:

Evaluation continues

Justification (if necessary):

Inspection for 'Pseudomonas syringae pv. morsprunorum' is recommended in EPPO Standard PM 4-30 Certification scheme for almond, apricot, peach and plum. However, in the responses to the questionnaire, DE and FR supported deregulation; DE arguing that feasible and effective measures were not available. FR considered that, if not deregulated, thresholds should be adapted. Evaluation continues on the measures.
Remark: The assessment performed covers the given host species as well as interspecific hybrids with other Prunus species.

4 - Are the listed plants for planting the main* pathway for the "pest/host/intended use" combination? (*: significant compared to others):

Conclusion:

Not candidate

Justification:

Only Prunus spp. are considered to be significant hosts of Pseudomonas syringae pv. morsprunorum (CABI, 2021). P. syringae pv. morsprunorum has been reported on peach (Ahmed et al., 2018) – Psm1 (P. amygdali pv morsprunorum), but seems to be rare.
P. syringae pv. morsprunorum overwinters in cankers and other diseased tissues, in contaminated buds and occasionally in the tree's vascular system. In spring, bacteria associated with overwintering sites are disseminated by splashing rain on to blossoms, fruits and leaves. Bacteria in dormant buds colonize blossoms and leaves as they unfold. Epiphytic populations of P. syringae pv. morsprunorum develop on the surface of symptomless blossoms and leaves from bloom through to leaf fall in the autumn (Crosse, 1966; Hattingh et al., 1989; cited from CABI, 2021).

Considering its very widespread distribution, the Fruit SEWG concluded that plants for planting was not a significant pathway compared to natural spread.

5 - Economic impact:

Are there documented reports of any economic impact on the host?

Justification:

Mean disease incidence was recorded as 49% on a cultivar locally known as 6 1/2 (Ahmed et al., 2018).

What is the likely economic impact of the pest irrespective of its infestation source in the absence of phytosanitary measures? (= official measures)

Is the economic impact due to the presence of the pest on the named host plant for planting, acceptable to the propagation and end user sectors concerned?

Is there unacceptable economic impact caused to other hosts (or the same host with a different intended use) produced at the same place of production due to the transfer of the pest from the named host plant for planting?

Conclusion:

Justification:

6 - Are there feasible and effective measures available to prevent the presence of the pest on the plants for planting at an incidence above a certain threshold (including zero) to avoid an unacceptable economic impact as regards the relevant host plants?

Conclusion:

Justification:

Planting trees that are budded or grafted about 32 inches above the root crown can help suppress bacterial canker infections. Bacterial canker tends to mostly affect weak trees, so any management practice that improves tree vigour (e.g., lighter, more frequent irrigation, improved tree nutrition, nematode management, etc.) will help to reduce the incidence of this disease (UC PMG, 2017).

7- Is the quality of the data sufficient to recommend the pest to be listed as a RNQP?

Conclusion:

Justification:

CONCLUSION ON THE STATUS:

Disqualified: seems rare on peach and plants for planting is not considered to be a significant pathway compared to natural spread.

8 - Tolerance level:

Is there a need to change the Tolerance level:

Yes

Proposed Tolerance levels:

Delisting

9 - Risk management measures:

Is there a need to change the Risk management measure:

Yes

Proposed Risk management measure:

Delisting

REFERENCES:

Ahmed R, Inam-ul-Haq M, Shahzad U, Hyder S, Shahzaman S, Khan AUR, Aatif HM, Ahmad A & Gondal AS (2018) First report of bacterial canker caused by Pseudomonas syringae pv. morsprunorum race 1 on peach from Khyber Pakhtunkhwa Province of Pakistan. Plant Disease 102, 2027. 10.1094/PDIS-10-17-1618-PDN
CABI (2021) Pseudomonas syringae pv. morsprunorum (bacterial canker of stone fruits) (accessed 12/Aug/2024). CABI Compendium. https://doi.org/10.1079/cabicompendium.44978.
Crosse JE (1966) Epidemiological relations of the Pseudomonad pathogens of deciduous fruit trees. Annual Review of Phytopathology 4, 291-310.
Hattingh MJ, Roos IMM & Mansvelt EL (1989) Infection and systemic invasion of deciduous fruit trees by Pseudomonas syringae in South Africa. Plant Disease 73(10), 784-789.